Fixing Npm Install Failures: React-native-formdata-polyfill

Jan 18, 2026 by Editorial Team 60 views

Hey guys, have you ever run into a situation where a seemingly innocent package throws a wrench into your whole project setup? I'm talking about those pesky npm install failures. Well, I recently wrestled with one, and it involved the @amityco/react-native-formdata-polyfill package. It's a handy tool for working with FormData in React Native, but a critical misconfiguration was causing headaches for anyone using it with modern ESLint versions. Let's dive into the issue, the root cause, and how to get your projects back on track. We'll also cover the current workarounds and the suggested fixes, so you can avoid this problem in the future.

The Problem: Incorrect Peer Dependency

The core of the problem lies in how the @amityco/react-native-formdata-polyfill package declares its dependencies. Specifically, it incorrectly lists eslint-config-eko@3.0.0 as a peer dependency. Now, peer dependencies are meant to specify that a package relies on a specific version of another package, but that other package should already be installed in the project. The problem with this setup, guys, is that eslint-config-eko is tied to a specific version of ESLint (7.32.0). This creates a conflict when you're using a newer version of ESLint, such as version 8 or 9, which is pretty common these days. The result? Your npm install command fails, leaving you staring at an error message. Let's explore how this impacts your project.

This incorrect dependency declaration forces your project to adhere to an outdated ESLint configuration. When you attempt to install the package, npm's dependency resolution struggles to find a compatible ESLint version. Essentially, the polyfill demands an older ESLint version while your project likely requires a newer one. This conflict leads to the dreaded ERESOLVE error, making it impossible to install the necessary packages. This is not ideal because developers are forced to choose between the polyfill and the modern ESLint version, which hinders the project's progress.

The Error Message Decoded

Let's break down the error message, so you understand what's happening under the hood. The error message is a bit of a wall of text, but here's a simplified explanation:

npm error code ERESOLVE
npm error ERESOLVE unable to resolve dependency tree
npm error
npm error While resolving: offshift@1.0.0
npm error Found: eslint@9.39.2
npm error node_modules/eslint
npm error dev eslint@"^9.0.0" from the root project
npm error
npm error Could not resolve dependency:
npm error peer eslint@"7.32.0" from eslint-config-eko@3.0.0
npm error node_modules/eslint-config-eko
npm error peer eslint-config-eko@"3.0.0" from @amityco/react-native-formdata-polyfill@1.1.5
npm error node_modules/@amityco/react-native-formdata-polyfill
npm error @amityco/react-native-formdata-polyfill@"^1.1.5" from the root project
npm error
npm error Fix the upstream dependency conflict, or retry
npm error this command with --force or --legacy-peer-deps
npm error to accept an incorrect (and potentially broken) dependency resolution.

npm error code ERESOLVE: This indicates a dependency resolution failure.
Could not resolve dependency: peer eslint@"7.32.0" from eslint-config-eko@3.0.0: This is the heart of the problem. It highlights the conflict between the required ESLint version by eslint-config-eko (7.32.0) and the one in your project (likely a newer version).

This message explains the core of the problem: a conflict between the outdated ESLint version required by the polyfill and the current version in your project. It's like trying to fit a square peg into a round hole; the dependencies aren't compatible, and npm can't resolve the conflict.

Root Cause Analysis: Why This Happened

To understand the root cause, let's peek inside the package.json file of the problematic package. Here's what we find:

Dependencies:

{
 "eslint-plugin-import": "^2.25.2"
}

Peer Dependencies:

{
 "eslint-config-eko": "3.0.0"
}

Dev Dependencies:

{
 "eslint": "^8.2.0",
 // ... other dev dependencies
}

The fundamental issue is the declaration of eslint-config-eko as a peerDependency. A FormData polyfill, whose primary function is to provide the missing FormData functionality in React Native environments, should not impose any specific ESLint configuration requirements on the projects that use it. ESLint configurations are development-time tools that should not interfere with runtime dependencies or introduce conflicts. The presence of eslint-config-eko in peer dependencies essentially forces the consumer projects to downgrade or deal with compatibility issues. Additionally, listing eslint-plugin-import as a runtime dependency also seems incorrect for a polyfill library, as it is related to code linting and not necessary for the polyfill to function correctly.

Dependency Conflict Chain: Unraveling the Web

Let's visualize the dependency chain, so you can see how this all connects:

@amityco/react-native-formdata-polyfill@1.1.5
└── peerDependency: eslint-config-eko@3.0.0
 └── peerDependency: eslint@7.32.0 (exact version)
 └── peerDependency: eslint-config-airbnb-base@14.2.1
 └── peerDependency: eslint-config-prettier@8.3.0
 └── peerDependency: eslint-plugin-import@2.24.2
 └── peerDependency: eslint-plugin-prettier@4.0.0
 └── peerDependency: prettier@2.4.0

As you can see, the @amityco/react-native-formdata-polyfill brings in eslint-config-eko, which, in turn, pulls in a specific version of ESLint and a whole bunch of other related packages. This is where the conflict arises. The project is forced to adhere to an outdated ESLint configuration due to this dependency chain. The polyfill should not dictate the ESLint setup of the projects that use it; it should be a standalone package that provides the FormData functionality.

Affected Versions: A Look at the Damage

The problem isn't isolated to a specific version; all published versions of the package are affected:

1.1.1 (2022-01-26)
1.1.2 (2022-01-26)
1.1.3 (2022-02-02)
1.1.5 (2022-02-19)

This means that any React Native or Expo project using any of these versions will likely run into the issue if they're using a modern ESLint version.

Expected Behavior: What Should Happen

Ideally, the package should not have eslint-config-eko as a peer dependency. ESLint and its configurations are tools for development and should not be a concern for the consumers of the package. The polyfill should provide the FormData functionality without imposing any specific ESLint requirements on the project.

Suggested Fix: A Path to Resolution

The fix is straightforward: the maintainers of the @amityco/react-native-formdata-polyfill package should remove eslint-config-eko from the peerDependencies section. They should also move eslint-plugin-import from dependencies to devDependencies in the package.json file. This change ensures that the polyfill doesn't force a specific ESLint configuration on the projects that use it.

Current Workaround: Bypassing the Issue

Until the package is updated, there's a workaround: using the --legacy-peer-deps flag with your npm install command. The command looks like this:

npm install --legacy-peer-deps

This flag tells npm to ignore the peer dependency conflicts and install the packages anyway. However, this is not an ideal solution, guys. While it allows you to bypass the issue and continue development, it can potentially lead to other problems. It's best to fix the root cause rather than relying on workarounds. You are essentially telling npm to resolve the dependencies in a way that might not be fully compatible, so you might encounter unexpected issues down the line.

Environment Details: A Snapshot of the Setup

Here are the details of the environment where this issue was observed:

OS: macOS 15.1 (Sequoia)
Node.js: v25.2.1
npm: 11.6.2
Package version: @amityco/react-native-formdata-polyfill@1.1.5

These details help to highlight the specific context in which the problem was encountered.

Additional Context: The Bigger Picture

It is important to note that the @amityco/react-native-formdata-polyfill package hasn't been updated since February 2022. This lack of updates means that the issue will continue to affect any React Native or Expo project that uses this package, particularly those using current ESLint versions (ESLint 9.x is the current major version as of 2024). This underlines the need for a fix. This problem will continue to plague projects until the maintainers address the dependency issue.

I hope this helps you guys avoid the headaches this issue caused me! Remember to stay up-to-date with your dependencies and keep an eye out for these types of conflicts, so you can keep your projects running smoothly. Have a great day!